Parametric curve question (determining unknown point)

  • #1
cherry
17
6
Homework Statement
A curve given parametrically by (x, y, z) = (3 - t, -1 - 3t^2, 2t + 2t^3). There is a unique point P on the curve with the property that the tangent line at P passes through the point (2, 8, 12). What are the coordinates of point P?
Relevant Equations
(x, y, z) = (3 - t, -1 - 3t^2, 2t + 2t^3)
My work so far:
IMG_5937C097F81C-1.jpeg


I am stuck because when I inputted the two possible values of t and k, neither solution worked. Where did I go wrong? Pointers would be appreciated! :)
 
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  • #2
cherry said:
Homework Statement: A curve given parametrically by (x, y, z) = (3 - t, -1 - 3t^2, 2t + 2t^3). There is a unique point P on the curve with the property that the tangent line at P passes through the point (2, 8, 12). What are the coordinates of point P?
Relevant Equations: (x, y, z) = (3 - t, -1 - 3t^2, 2t + 2t^3)

My work so far:
View attachment 338514

I am stuck because when I inputted the two possible values of t and k, neither solution worked. Where did I go wrong? Pointers would be appreciated! :)
I see where I went wrong and it turns out t = -1 and k = 2 is the correct solution.
Where would I go from there to determine point P?
 
  • #3
cherry said:
I see where I went wrong and it turns out t = -1 and k = 2 is the correct solution.
Hello @cherry, and
:welcome: ##\qquad## !​

Kudos for finding out!
1705184825929.png
is indeed 12, not 16. (*)

cherry said:
Where would I go from there to determine point P?
You have ##(x, y, z) = (3 - t\; , -1 - 3t^2\; , 2t + 2t^3) \ !##(*) quoting is a lot easier if ##\LaTeX## is used. See link to guide at lower left of edit window...

[edit] I didn't check if k=2 is the correct solution, nor whether the other solution is invalid
[edit] did now.

##\ ##
 

1. How do you determine an unknown point on a parametric curve?

To determine an unknown point on a parametric curve, you need to first express the curve in parametric form, then substitute the parameter value into the equations to find the corresponding coordinates of the point.

2. Can you provide an example of determining an unknown point on a parametric curve?

Sure! Let's say we have a parametric curve defined by x(t) = 2t and y(t) = t^2, and we want to find the point at t = 3. By substituting t = 3 into the equations, we get x(3) = 6 and y(3) = 9. Therefore, the unknown point on the curve is (6, 9).

3. What is the significance of parametric curves in mathematics?

Parametric curves are important in mathematics as they allow us to represent complex curves and shapes using simpler equations. They are also useful in describing motion, such as the trajectory of a projectile or the path of a moving object.

4. How do you plot a parametric curve on a graph?

To plot a parametric curve on a graph, you can first create a table of values by choosing different values for the parameter. Then, plot the corresponding points on the graph and connect them to form the curve. Alternatively, you can use software or online tools to plot parametric curves accurately.

5. What are some common parametric curves encountered in mathematics?

Some common parametric curves encountered in mathematics include circles, ellipses, parabolas, and spirals. These curves can be described using parametric equations that involve trigonometric functions or other mathematical operations.

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